It has long been known that odors from various sources are difficult to control, including malodors associated with bodily fluids, feces, putrefying organic wastes, combustion by-products, and the like. Two common strategies of malodor control are sorption and fragrance masking. When used individually and/or in combination these strategies often provide limited and/or unsatisfactory odor control for obnoxious odors like those associated with feces, stale urine, menses, vomitus, tobacco smoke, fish, putrefying food wastes, and the like.
The most common reason for failure of a pure sorption strategy to control malodors is that, in the absence of 100% sorption of malodors, many residual non-sorbed malodors at parts per billion (ppb) levels or lower are perceived as obnoxious by humans. Near 100% sorption of malodors, which can be insufficient for success, is not easily attained in practice, but is sometimes approachable with a very high degree of malodor containment and/or the use of excess sorbent.
The most common reason for failure of a pure fragrance masking strategy to control obnoxious odors is that the amount of fragrance sufficient to mask the malodors is often just as obnoxious to those concerned with the problem as the malodors themselves. In addition, delivery of sufficient fragrance to mask strong malodors is difficult to achieve for any extended period of time due to rapid dispersion of the fragrance. Moreover, a method for as-needed, automated delivery of appropriate levels of masking fragrance has not existed in the past; hence, human intervention for delivery is needed.
Other reasons for failure common to both the sorption and fragrance masking strategies are a) the variety of individual malodor components from any given source and b) the variable presence of the various individual malodor components during any given malodor event. For example, while activated carbon has long been known to excel at sorbing a wide variety of malodors, no single sorbent is capable of sorbing all of the various malodor components that can be associated with many sources of strong malodors, such as feces, menses, vomitus, putrefying organic waste, and the like. Activated carbon, even when dosed with an adjuvant material such as citric acid or copper, is a relatively modest sorbent for ammonia, hydrogen sulfide, methyl mercaptan and other malodors from such sources. In addition, for any of the strong malodor sources the specific malodors will vary among sources and/or over time within sources. A mixture of various sorbents could, in theory, provide sorption capacity for all possible malodors, but oftentimes much of the sorbent mixture would be unnecessary or wasted when contained in durable articles or disposable articles. In the case of fragrance, it is difficult—perhaps impossible—to formulate any one fragrance composition capable of masking successfully so many different possible combinations of malodors.
The use of a combination of sorption and fragrance masking to achieve odor control has been proposed in the past, but has not been commercially adapted nor readily achieved for several reasons. Some relevant art teaches that use of a fragrance to mask malodor in absorbent articles may detract from the functionality of the malodor sorbent, presumably from the fragrance occupying sorption sites on the sorbent needed for malodor sorption, but no specific methods nor criteria are provided to overcome this problem. Other publications teach placing the malodor sorbent and the fragrance release source on opposite sides of a forced-air circulation system such that the malodors are sorbed prior to the deodorized air being distributed back to the room with fragrance; however, in practice, fragrance is eventually returned to the forced-air unit to be sorbed thereby substantially reducing fragrance delivery. None of these published odor control solutions adequately overcome problems of linking fragrance release to the malodor occurrence and concurrently controlling losses of fragrance from the odor composition when fragrance masking is unnecessary.
For moisture-activated compositions many sources of malodor such as feces, menses and combustion by-products have insufficient moisture to activate adequate fragrance release, and/or the initial presence of sufficient moisture does not coincide with the bulk of the malodor release, and/or the amount of fragrance release is insufficient to mask strong malodors. Moreover, previously published data demonstrate that fragrances are poorly retained by a sorbent carrier in the absence of a protective device or encapsulation such that fragrance is released continuously irrespective of the presence of malodors. At best what is claimed for such inventions is durable fragrance release. In contrast, the rate of fragrance release from a chemical bond can be better controlled. But, fragrance release is too slow compared to the rate of malodor dispersion. Finally, when thermal energy is used to release fragrance, the fragrance delivery system does not work or tends to work poorly under ambient conditions, i.e., in the absence of heat.
In summary, all of the previously proposed solutions lack direct linkage of fragrance release to the malodor source, i.e., none use malodors to directly trigger fragrance release or to provide fragrance release proportional to the malodors to be controlled.
Accordingly, the present invention overcomes the problems associated with controlling malodors by a combination of sorption and fragrance masking in an efficient and effective manner for a wide variety of applications. The present invention is useful for consumer products and other applications intended to control a variety of malodors, such as from bodily fluids, putrefying organic wastes, combustion by-products, and the like, in a cost-effective manner using shelf-stable articles that minimize unnecessary, untimely, and/or excessive fragrance masking.